Amine-thiazyl disulphide reaction product



Patented Dec. 31, 1940 1 UNITED STATES PATENT orri cs AMINE-THIAZYL DISULPHIDE REACTION PRODUCT Marion W. Harman, Nitro, W. Va.., assignor to Monsanto Chemical Company, St. Louis, Mo., a corporation of Delaware No Drawing. Original application April 11, 1933, Serial No. 665,568. Divided and this application October 16, 1937,

10 Claims.

The present invention relatesto the art of rubber manufacture and particularly relates to a new class of rubber vulcanization accelerators for use in the vulcanization of rubber and rubberlike products. ii

The new and preferred class of rubber vulcanization accelerators comprise the reaction products of an isocyclic saturated organic base and members of a class or organic compounds possessing the grouping wherein R is nitrogen, carbon or sulphur, X is are the compounds tetramethyl thiuram disulphide, tetraethyl thiuram disulphide and tetramethyl thiuram polysulphide. As examples of the above class of compounds wherein R is sulphur, X is nitrogen and Y is the acidic hydrogen atom of a mercaptothiazole are the compounds mercapto-benzo-thiazole, mercapto-tolyl-thiazo'le and mercapto-naphtha-thiazole. As examples of the above class of compounds wherein R is sulphur, X is nitrogen and Y is sulphur are diibenzo-thiazyll disulphide and polysulphide. In mercapto-benzo-thiazole, mercapto-tolyl-thiazole, mercapto-naphtha-thiazole, diEbenzo-thiazyll-disulphide and diEbenzo-thiazyl] polysulphide R andX are part of a ring.

Examples .of isocyclic bases that are reactive with the organic" compounds hereinbefore set forth, possessing the grouping 1 are decahydro beta 'na'phthylamine; decahydro alpha naphthylamine, bornyl amine, methyl bornyl amine, ethyl bornyl amine,- dibornyl amine, caryl amine, cyclohexyl ethyl amine,cyclohexyl methyl amine, 1-methy-1-4-amino hexahydrobenzene, cyclohexyl amine and dicyclohexyl amine. The compounds thus obtained-are typical members of the new and preferred class of rubber Serial No. 169,472

vulcanization accelerators and are included within the scope of the present invention.

The following are to be understood as illustrative embodiments of the invention and not limitative of the scope thereof.

EXAMPLE I Substantially equi-molecular proportions of cyclohexyl amine and mercapto-benzo-thiazole' were dissolved in boiling alcohol. After solution thereof was effected, the resulting solution as cooled and the cyclohexyl amine salt of mercapto-benzo-thiazole, which separated out was filtered off and dried. The desired reaction product was obtained in high yield and in nature was a crystalline material melting at substantially 151-155" C. The product thus obtained wasincorporated in the usual manner in a typical rubber gum stock comprising Parts Pale crepe rubber Zinc oxide I 5 Sulphur "3 Stearic acid f 1 Accelerator 0.25

The rubber stock thus compounded .was vulcaniz'ed and the cured rubber product tested with the following results. v

From the data set forth in Table I, it is readily apparent that the new and preferred class of accelerators, for example the reaction product of cyclohexyl amine and mercapto-benzo-tliiazole, are markedly strong in their accelerating effect, as 0.25% of accelerator based on the rubber content gives substantially as" high a state of cure as 1% of most of the commercial accelerators.

The reaction product of cyclohexyl amine and mercapto-benzo-thiazole described above was also employed in a typical rubber tread stock comprising Parts Smoked sheet rubber Carbon black 50 Zinc oxide 5 Sulphur 3 Stearic acid 3 Pine tar 2 Accelerator 1 The rubber stock thus compounded was vulcanized and the cured rubber product tested with the results obtained as set forth in Table II.

The data set forth inTable II show that the new class of accelerators, for example the reaction product of cyclohexyl amine and mercaptobenzo-thiazole, are also markedly efficient in rubber tread stocks. a r

If desirable, the new and improved class of accelerators may be employed in conjunction with basic organic nitrogen containing accelerators. Thus, on employing the reaction product of cyclohexyl amine and mercapto-benzothiazole in conjunction with diphenyl guanidine, said reaction product is activated therebyand its accelerating action increased. Other basic organic nitrogen accelerators, as for example triphenyl guanidine and di ortho tolyl guanidine, may be similarly employed.

EXAMPLE II t The reaction product of substantially equimolecular proportions of dicyclohexyl amine and mercapto-benzo-thiazole was prepared in a manner analogous to. that employed in the preparation of Example I. The product so obtained was a pale yellow solid melting at I'll-172 C. The reaction product of dicyclohexyl amine and mercapto-benzo-thiazole prepared as described above was incorporated in a rubber stock comprising Parts Pale crepe rubber 100 Zinc oxide 5 Sulphur 3 Stearic acid p 1 Accelerator 0.5

After vulcanizing, the cured rubber product was found to possess the following tensile and modulus characteristics.

Table III Modulus ofelasticity in lbs./1n." at elongatlons of- Tensile It at lglrleak elongq Lbs. ling percent Mlns. steam 300% 500% v 700% pressure EXAMPLE III Substantially one molecular proportion of a mixture of substantially 50% of cyclohexylamine and 50% of dicyclohexyl amine was reacted with substantially one molecular proportion of mercapto-benzo-thiazole by adding the above reactants to a suitable amount of Water so as to form a paste and intimately mixing and grinding the mix by any convenient means, as for example by agitating in a ball mill. Some heat of reaction developed. It is preferred, however, to maintain the-reaction temperature at substantially 40 to 45 C. in order to avoid loss of the amine during the reaction. After completion of the reaction, the resulting solid is preferably removed from the reaction mass, as forexample by filtration, and dried. The dried crystalline product prepared as described, melted at substantial1y135 to C. The product prepared as described was incorporated in a gum stock comprising I Parts Pale crepe rubber 100 Zincoxide 5 Sulphur 3 Stearic acid 1 Accelerator 0.5

The compounded rubber stock wasthen vu1- canized and the cure-d rubber product found to possess the modulus and tensile characteristics given in Table IV.

Substantially one .molecular proportion of dilbenzo-thiazyl]-disulphide and substantially two molecular proportions'of cyclohexyl amine were allowed to react at room temperature. :The heat of reaction caused a rise in temperature to substantially 60 C. Heating was continued for substantially one hour at substantially 60 C. The product thus formed was. a hard grindable solid, which was incorporated in a rubber stock in the usual manner comprising Parts Pale crepe rubber--. 10 Zinc oxide 5 Sulphur 3 Stearic acid 1 The reaction product of dibenzo-thiazyl disulphide and cyclohexyl' amine 0.5

aaaoyer The compounded rubber stock on vulcanizing and testing gave the following results.

The compounded stock described above, wherein the reaction product of diibenzo-thiazyll-disulphide and cyclohexylamine was employed as an accelerator, showed no set up or prevulcanization as determined by the Williams plastometer described by Williams, Industrial and Engineering Chemistry for 1924 (vol. 16, page 362see also Krall, ibid, vol. 16, page 922) on heating for 120 minutes at 200 F.

EXAMPLE V Substantially one molecular proportion of tetramethyl thiuram disulphide and substantially two molecular proportions of cyclohexyl amine were allowed to react at room temperature. The heat of reaction caused a rise in temperature to substantially 50 C. After further heating at 60 C. to complete the reaction, the product was allowed to cool. The resulting product, comprising a yellow solid, was incorporated in a typical gum stock and found to possess the accelerating properties typical of the preferred class of new accelerators.

From the data hereinbefore set forth, it is readily apparent that the preferred class of vulcanization accelerators comprise a group of compounds that are particularly strong in their accelerating action properties and that the vulcanized rubber in which they are employed retains its desirable properties on continued vulcanization; that is to say it does not readily over cure. If it is desirable to further slow down the acceleration of the preferred class of accelerators, this may be accomplished by employing therewith certain retarding agents, as for example aniline acid phthalate and diphenyl guanidine phthalate. Aniline acid phthalate has the structural formula of Parts Pale crepe rubber 100 Zinc nxidp Sulphur 3 Stearic acid 1 The reaction product of cyclohexyl amine and mercapto-benzo-thiazole Diphenyl guanidine phthalate Thecompounded stock set forth above showed no set up or prevulcanization, as determined by the Williams plastometer described above on heating for 240 minutes at 200 F.

- A rubber tread stock was compounded comprising I Parts Smoked sheet rubber 100 Carbon black 50 Zinc nsri de 5 Sulphur r 3 Stearic acid 3 Pine tan 2 The reaction product of cyclohexyl amine and mercapto-benzo-thiazole 0.5 Aniline acid phthalate 0.5

Plastometer. tests carried out as above deazole and a mixture of 50% of cyclohexyl amine and 50% of dicyclohexyl amine has also been employed in typical gum and tread stocks in conjunction with aniline acid phthalate and diphenyl guanidine phthalate, and the rubber stock found on test to be free from scorching properties.

The present invention is limited solely by the following claims, wherein it is intended to claim the invention as broadly as possible. Products formed by means of an oxidative condensation reaction are claimed in Serial No. 220,341 filed July 20, 1938, now U. S. Patent 2,191,657 and no claim is made thereto in the instant application.

This is a division of co-pending application Serial No. 665,568, filed April 11, 1933, now Patent 2,100,692.

What is claimed is:

1. A product obtained by reacting at room temperature in the absence of oxidizing agent an intimate mixture consisting of a saturated isocyclic primary amine and a' thiazyl disulphide in the ratio of substantially two molecular proportions of amine to one of thiazyl disulphide and heating the mixture.

2. A product obtained by reacting at room temperature in the absence of oxidizing agent an intimate mixture consisting of a saturated isocyclic primary amine and an aryl thiazyl disulphide in the ratio of substantially two molecular proportions of amine to one of thiazyl disulphide and heating the mixture.

3. A product obtained by reacting at room temperature in the absence of oxidizing agent an intimate mixture consisting of a cyclohexyl primary amine and an aryl thiazyl disulphide in the ratio of substantially two molecular proportions of amine to one of thiazyl disulphide and heating the mixture.

4. A product obtained by reacting at room temperaturein the absence of oxidizing agent, an intimate mixture consisting of a cyclohexyl primary amine and a benzothiazyl disulphide in the ratio of substantially two molecular proportions of amine to one of thiazyl disulphide and heating the mixture.

5. A product obtained by reacting at room temperature in the absence of oxidizing agent, an intimate mixture consisting of cyclohexylamine and di(benzothiazyl) disulphide in the ratio of substantially two molecular proportions of amine to one of thiazyl disulphide and heating the mixture.

6. A process of preparing an amine, thiazyl disulphide reaction. product which .comprisesreacting at room temperature in the absence .of oxidizingxagent an intimate mixture consistingzof a saturated isocyclic'primary amine andi'a thiazyl disulphide in the ratioof substantially two molecular proportions of amine to one of thiazyl. di sulphide and heating the mixture.

7 A process of preparing anamine,t thiazyl disulphide lr u KQdU- t .W 1 P mPW M wri e om t tur in t e ebeenee at w re dizing agent an intimate mixture consisting -o a saturated isocyclic primary amine and an ar yl thiazyl disulphide inthe ratio of substantially two molecular proportions of amine to one of thiazyl disulphide andheatingthe mixture. I

8. A process of preparing an amine, thiazyl disulphide reaction product which comprises reacting at room temperature in the absence of. oxidizing agent an intimate mixture consisting of a cyclohexyl primary amine and an aryl .thiazyl disulphide the ratio :of substantially two molecular proportions of. aminejtoone or thiazyl disulphide and. heating the mixture.

9. A process of preparin'g'an amine, thiazyl disulphide reaction product which comprises reacting; at room temperature in the absence of oxidizingagent, an' intimate mixture consisting of a cyiclohex yl primary amine and a benzothiazyl disulphide-in the ,ratio of substantiallyftwo molecular proportions of amine to one of'thiazyl disulphide and heating the mixture. l0. A process of preparing, an amine, thiazyl disulphide reaction product 1 which 1 comprises. reacting at room temperature in the absence of oxidizing agent, an intimate mixture consisting offcyclohexylamine and di(benzothiazyl) disulphide in the ratio of substantially two molecular proportions of amine to one of thiazyl disulphide and heating the mixture.

MARION Wu 1 20 

